title: Quantification of aerobic energy turnover in epididymal bull spermatozoa.
abstract: Turnover rates of oxidative energy metabolism were measured as oxygen consumption in untreated and caffeine-stimulated epididymal bull spermatozoa respiring with lactate. Incubation of spermatozoa with 1 mM caffeine led to an increase in respiration of approx. 60%. The rate of uncoupled respiration and the vanadate-insensitive part of oxygen consumption were not affected by caffeine. The small effect of ouabain on respiration (-10%) indicated a minor contribution of Na+/K+-ATPase to the ATP consumption. The major part of ATP turnover was caused by motility shown by the strong linear correlation between respiration and motility in untreated and caffeine-treated spermatozoa. In comparison with ejaculated spermatozoa investigated in a previous study, epididymal cells exhibited the same rates of uncoupled and ouabain-sensitive respiration. The efficiency of transforming mitochondrially-produced ATP into cell motion was the same in epididymal and ejaculated spermatozoa. The ATP-producing capacity of sperm mitochondria was utilized in untreated epididymal, in caffeine-stimulated epididymal and in ejaculated spermatozoa, by 20-25%, 40-45% and 45-50%, respectively. The results showed that the capacity of mitochondrial. ATP formation remains unchanged after ejaculation and is utilized to a higher extent by stimulated motility. Treatment with caffeine affected epididymal spermatozoa in a similar manner.
authors.affiliation: Institut für Biochemie der Medizinischen Akademie Magdeburg, G.D.R.
authors.forename: W
authors.initials: W
authors.lastname: Halangk
authors.forename: U
authors.initials: U
authors.lastname: Tröger
authors.forename: R
authors.initials: R
authors.lastname: Bohnensack
mesh_terms: D000332:Aerobiosis; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002417:Cattle; D004734:Energy Metabolism / Q000187:drug effects; D004822:Epididymis; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D010101:Oxygen Consumption; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000378:metabolism*; D014639:Vanadium / Q000494:pharmacology
chemical_list: D014639:Vanadium; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D002110:Caffeine; D010042:Ouabain